1. Field of the Invention
The present invention relates to systems for storing and recycling heat, and more particularly, to a system for, and method of, storing and recycling first and second quantities of process heat from a vapor having substantially the total initial process heat.
2. Description of the Prior Art
Conventional systems which produce heat energy for use in various apparatuses, such as steam sterilizers, washer sterilizers, and laundry and distillation equipment, generally do not consume all the heat produced for use in the processes (process heat) practiced in those apparatuses. Following the phase of the process in which the heat is utilized, the remaining, unconsumed process heat energy is cooled and vented into the atmosphere or drained.
In sterilizers, where only about 4% of the heat energy input is consumed during the process, the steam is typically exhausted from the chamber, condensed and subcooled with large volumes of water. Current plumbing codes require the temperature of drained water to be no greater than 140.degree. F. Steam having a temperature of at least 212.degree. F. may require in excess of three hundred gallons of water per hour to cool it to acceptable temperature levels. The large volumes of hot water cannot be recirculated in the conventional sterilizer systems. Cool water is used to pull vacuums through the piping network of steam sterilizers. Water having elevated temperatures will not effectively pull the vacuum, therefore, the water heated by the condensing steam cannot be used within the vacuum piping network and must be drained. The result is that the heat energy is lost and large volumes of water are required, providing a costly, inefficient system.
Systems for the storage of heat energy for later use have been disclosed in U.S. Pat. Nos. 3,977,197 and 4,094,148. Both of the systems described in those patents use heat energy to drive a turbine which in turn produces electricity. When the potential that initially produces the heat, produces more than can be immediately used by the system, the excess heat is stored. When the systems require more heat energy, for example during peak electricity demand hours, the stored heat energy is directed to the turbine for production of more electricity. Neither system returns the heat energy to the potential that fed the system initially. The process heat energy is not recaptured, but is stored for eventual consumption of the heat energy in the process at a later time. Neither system is adapted for use with processes that do not consume the process heat energy.
Accordingly, there is a need for a system and a method for storing and recycling the process heat energy generated for use in apparatuses which do not consume a substantial portion of that heat energy. There is a further need for such a system and a method which promotes more efficient and less costly use of all the resources associated with the system.